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VAC 70/70 mk3 tube rolling question

I recently purchased a VAC 70/70 mk3 s. Where can I find more information about the tubes diagram for the amp? I know it uses two 6sn7 per channel. Are there any differences in functionality between the two 6sn7 used for each channel? For example, do I need to use a matching pair of 6sn7 per channel?

I have one matched pair of RCA red base 6sn7 and a matched pair of Raytheon vt231 6sn7. The RCA are good for lush mids with 3d soundstage and Raytheon vt231are good for speed and accuracy.

They were meant to be used for the Schiit freya plus which uses a pair of 6sn7 for output stage and another pair of 6sn7 for voltage gain stage. Now since I already get a VAC renaissance 5 preamp, I am wondering if I can use my two pairs of 6sn7 on the VAC 70/70 amp.

My question is can I use one RCA + one Rayheon vt231 for each channel of the VAC? Or should I use a matched pair of 6sn7 for each channel? What are the recommended settings?

Also, any experiences about tube rolling on the VAC 70/70 mk3 are welcome. Like which 300B amps or 6sn7 combinations give you the best results.
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yuhengdu_tiger's avatar
yuhengdu_tiger OP
87 posts
 
@lowrider57  Thanks for the helpful information. Forgive me as I don't understand all the details of the williamson circuit and I can't upload photos here. 

So basically there are four 6sn7 tubes in the front row of 70/70. Assume they are V1, V2, V3, V4 from left to right. My understanding is that V1, V2 are for channel 1, and V3, V4 are for channel 2, is that right?

My question is which ones are for gain stage and which ones are for phase inverters? ( If my above assumption is right, is v1, v3 for gain stage; v2, v4 for phase inverters ?) Thanks!  
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lowrider57
5,417 posts
 
Correct, V1,V2 for left channel.
V3,4 for rt. channel.

Sorry, I can't help identify which is gain and which is driver. Hopefully a VAC owner will chime in.
But, designers like to keep things organised, so I would guess that the gains are V1 and V4. Or they could be V2 and V3.

Have you looked for a user manual online?

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drrsutliff
864 posts
 
Call the VAC factory and speak to Kevin or Brent. I believe the order will be the two most outside (L and R) should match and the two inner should match, but my memory may be incorrect.  They are always happy to welcome new members into the VAC family and will share where they believe each pair will work best (splitter or gain) and exactly which pair of tube sockets is each... so yes one of each for each channel but you need to know which sockets are what in the circuit. If your “red base” RCAs are the 5692 military versions I would suggest those to be in the amplification section and use the others as the splitters.
The manual is on the VAC website if you have not already seen it. http://www.vac-amps.com/manuals/Manual_Ren70-70.pdf
yuhengdu_tiger's avatar
yuhengdu_tiger OP
87 posts
 
@rodman99999  Thanks a lot for these info! I purchased my two pairs of 6sn7 from Brent at audiotube.com. He helped me picking up those sets. Personally I don't have a lot of experiences with tube rolling. 
yuhengdu_tiger's avatar
yuhengdu_tiger OP
87 posts
 
@lowrider57  Yes I checked the user manual online here: http://www.vac-amps.com/manuals/Manual_Ren70-70.pdf

Unfortunately the Figures that shown the tube placement are missing. (figure 2).
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